The present application is directed to implanted devices for providing communication between internal strutures of the body and the exterior of the body. In particular, the application is directed to implantable structures for peritoneal dialysis applications.
Peritoneal dialysis is a process whereby dialysate solution is introduced into the peritoneal cavity for a period of time during which waste materials pass from the blood through the peritoneal membrane into the dialysate. The wastes are removed from the body by drainage of the dialysate from the peritoneal cavity. Peritoneal dialysis may be performed intermittently by machines which automatically fill and drain the peritoneal cavity, usually while the patient is sleeping. Another variation of the process, "continuous ambulatory peritoneal dialysis" (CAPD), has shown increasing use in recent years because, among other reasons, of its relatively low cost and ease of patient self-care and comparison to the more typical hemodialysis treatment. CAPD also allows a patient to engage in most normal life activities while undergoing dialysis. As typically practiced, CAPD utilizes a perforated catheter of a silicon elastomeric material, such as medical grade Dow SILASTIC.TM., implanted in the peritoneal cavity and extending through the abdominal wall. Sterile dialysate is infused into the peritoneal cavity by connecting the catheter to a container of dialysate and raising the container above the abdomen so as to the drain the contents into the peritoneal cavity. Prepackaged flexible plastic bags of dialysate offer the advantages that drainage may be accomplished without venting to the atmosphere and that the bag, when empty, may be left connected to the catheter and strapped around the patient's body during residence of the dialysate in the solution. After several hours, the bag is lowered below the abdomen, and the used dialysate fluid permitted to drain back into the bag. The catheter is then connected to a fresh dialysate container which is infused as described into the patient.
In spite of its obvious advantages, CAPD suffers from serious problems because of a frequent occurrence of peritonitis caused by bacterial infection in the peritonium. These infections are most typically caused by nonsterile technique in connecting the catheter to dialysate containers.
Infections may also occur at the exit site where bacteria may invade the body along the exit opening. Subcutaneous cuffs of Dacron.TM. (polyethylene terephalate) felt, adhesively joined to the catheter below the skin, have been used to provide tissue ingrowth media so as to achor the tubes and provide a scar tissue barrier to bacterial penetration; but, exit site infections remain a significant problem. This may be related to the flexible nature of the catheter at the exit site, the movement of which may facilitate bacterial penetration. Additionally, dimensional changes in the silicon catheter due to uptake of body fluids or gradual degradation thereof by body fluids may also contribute to the exit site infection problem.
A variety of implantable percutaneous devices have been described for providing external access to internal structures of the body, primarily of the circulatory system. Such structures typically embody flange means for anchoring the device below the skin layer. Porous tissue ingrowth media, such as velour cloth or Dacron felt have also been used with such devices to add to the anchoring ability of the subcutaneous flange members. As described in U.S. Pat. No. 3,783,868, however, such flanged devices exhibit a problem in that epithelium tissue progressively grows down and around the device, eventually encapsulating it and expelling it from the body.